The proposed peatland restoration site at Harwood is located approximate 1.3 km from the re-stock flux tower at Harwood Forest, which means the wind data used for this analysis are most representative of the condition on site.

Data

We used direct measurements from our flux site over 2015 to calculate the footprint. Similar to previous analysis, we used the Kormann and Meixne (2001) model with friction velocity, zero plane displacement, Monin-Obukhov length ans stability and standard deviation of the wind y-vector all derived from real measurements.

Two “scenarios” were investigated; two and three meter instrument installation with a 500 m fetch. We also looked at a wind rose to identify prevailing wind direction. Finally, footprints were plotted on Google Maps satellite imagery for better visualising the area of measurement.

Results

A wind rose plot showed the prevailing wind is from West, West-South-West direction. Instruments should be installed to reflect that. The most common wind speed is between 2-4 m/s.

Both scenarios were found to produce a footprint where there is 90% probability fluxes are coming within 300m of the tower. The tower was placed slightly off the centre of the main restoration area towards the North-East corner. Although Google Maps areal photography shows the tip of the footprint to be over forest, this is an old photograph and so the 3 m installation height scenario exteds to the felled or open area (see Richard Guy’s map). If the tower is placed in the proposed location it will be 700 meters from the edge of the Sitka spruce stand (P2000) on a West direction, well outside the footprint. On a South direction the tower will be approximately 300 m from the edge of the spruce stand (P81). However, the strong westerly winds result in a elongated footprint of about 100-150 meters on a South direction (for both installation height scenarios). The distance from the stand along the prevailing wind and the flat topography (slope < 1%) make it a potentially suitable location.